Effect of incorrect storage of bull semen samples on sperm morphology assessment

Abstract

Thirteen pairs of bull semen samples were assessed. One of each pair of samples was inadvertently stored in phosphate buffered saline (PBS) that was used for analysis of motility immediately after collection. Other sample of the pair that was correctly stored in buffered formol saline (BFS) was assessed later. Proportion of morphologically normal sperm was different (p = 0.0021) between the 2 storage methods. Most of the abnormalities in the PBS samples were loose and detached heads. Closer examination of these sperm illustrated changes in the composition of the tail, with an apparent loss of the plasma membrane. This serendipitous error allowed documentation of the importance of correct storage of semen samples for morphological assessment of sperm, and the tertiary defects detected with the incorrect storage of semen samples in semen extender. Tertiary defects should always be considered a possibility during morphological assessment of sperm via spermiogram.